Spirometer having individually characterized, single-use disposable sensor

ABSTRACT

An improved spirometry assembly (20) is provided which includes a spirometer (22) and a sensor unit (24) coupled via handle assembly (26). The spirometer (22) has a reading slot (30) as well as an optical reader (36). The sensor unit (24) includes a tab (72) having at least one characterizing indicium (76) thereon which characterizes a response parameter of the sensor unit (24) upon flow of gas therethrough. In use, the reading slot (30) receives tab (72) and the reader (36) reads the indicium (76) and generates characterizing data representative thereof which is sent to a signal processor within the spirometer (22). The assembly (20) includes a measuring device such as a pressure transducer in operative communication with the interior of the sensor unit (24) for measuring a condition therein during patient-induced gas flow and generates pressure data. The signal processor within the spirometer (22) receives both the pressure data and the sensor unit characterizing data and generates report information about a pulmonary condition of a patient.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is broadly concerned with an improved spirometryassembly for measuring one or more patient pulmonary parameters. Moreparticularly, the invention pertains to a spirometry assembly includinga spirometer having a base equipped with a reader (e.g., an elongatedreading slot with an adjacent optical reader) and a disposable tubularsensor unit having at least one characterizing indicium thereon readableby the reader. Preferably, the sensor unit has a tab including at leastone characterizing indicium thereon which characterizes a responseparameter of the sensor unit upon flow of gas therethrough. In use, thetab is inserted within the base slot and the characterizing indicium isread to generate characterizing data for the specific sensor unit; ameasuring device (e.g., a pressure transducer) is in operativecommunication with the interior of the sensor unit and is used togenerate condition data during patient-induced inspiratory or expiratorygas flow through the sensor. The characterizing data and condition dataare sent to a signal processor which generates a report about thepulmonary condition of the patient. The preferred sensor unit isequipped with a specialized pressure chamber which minimizes thepossibility of pathogen contamination during use.

2. Description of the Prior Art

Spirometry is considered to be one of the most basic and important teststhat measure pulmonary function, and is used in the prevention,diagnosis, observation and therapy of many pulmonary diseases such aschronic obstructive pulmonary disease (COPD). During spirometry, apatient induces an expiratory or inspiratory gas flow through asingle-use, disposable sensor tube equipped with a restrictor. Thepressure conditions within the sensor tube are measured via a sensitivepressure transducer, and this data is used to calculate in amicroprocessor-based signal processor various pulmonary flow conditionssuch as forced vital capacity (FVC), forced expiratory volume in thefirst second of expiration (FEV₁), FEV₁ /FVC, forced expiratory volumein the third second of expiration (FEV₃), mean flow rate between 25% and75% of the FVC (FEF25-75%), peak expiratory flow (PEF), forcedexpiratory time (FET), forced inspiratory vital capacity (FIVC), peakinspiratory flow (PIF), ratio of forced inspiratory flow at 50% of FIVCto the forced expiratory flow at 50% of FEC (FEF50%/FIF50%) and maximalvoluntary ventilation (MVV).

A persistent problem with existing spirometry systems stems from thefact that the single-use spirometry sensor tubes must be individuallycalibrated, or characterizing data for each such sensor tube must beprovided as an input to the spirometer signal processor. For example, inone widely used spirometry system sold by Nellcor Puritan BennettCorporation under the designation "Renaissance", the individual sensortubes having screen-type restrictors are factory-calibrated to insurethat pressure conditions therein during specified gas flow rateconditions are essentially constant. Such calibration operations arelabor intensive and therefore relatively expensive.

It has also been known in the past to provide characterizing data witheach individual sensor tube. In such systems, the user must enter thecharacterizing data into the spirometer so that such data can be used inthe overall calculations leading to a pulmonary report. These systemssuffer from the added complexity of requiring the user to enter thesensor tube characterizing data, and the possibility of data entry errorwhich can lead to an entirely erroneous pulmonary report.

Some prior spirometry sensor tube equipment has been prone tocontamination from aerosolized or other contaminants entrained withinexpiratory gas. This is a problem inasmuch as disease can be spread frompatient-to-patient through the spirometry equipment.

SUMMARY OF THE INVENTION

The present invention overcomes the problems outlined above and providesan improved spirometry assembly for measuring a pulmonary condition of apatient. Broadly speaking, the spirometry assembly of the inventionincludes a base and a tubular sensor unit operatively coupled to thebase. The sensor unit carries at least one characterizing indicium whichcharacterizes a performance parameter of the sensor unit, and thespirometer has an indicium reader operatively coupled thereto forreading the sensor unit indicium and providing such information to thesignal processor of the spirometer. Preferably, the base presents anelongated reading slot and is equipped with a reader adjacent thereading slot. The sensor unit comprises an elongated tubular elementhaving a reading tab, the latter having at least one characterizingindicium which characterizes a response parameter of the tubular elementupon measured flow of gas therethrough. In use, the reading slotreceives the tab and the reader reads the indicium information andgenerates characterizing data which is sent to a microprocessor-basedsignal processor housed within the base. Next, the patient induces a gasflow (either inspiratory or expiratory) through the tubular element, anda measuring device in operative communication with the interior of theelement measures a condition therein and generates representativecondition data which is also sent to the signal processor. In the signalprocessor, the characterizing data and condition data is used togenerate report information about the pulmonary condition of thepatient.

In preferred forms, the measuring device is in the form of the pressuretransducer and A to D converter which is housed within the base alongwith the signal processor. Thus, during the patient-induced pulmonarygas flow, the pressure conditions over time within the tubular elementare measured. Pressure condition data is then mathematically converted,using the specific characterizing data for the sensor unit used, to givea pulmonary report about the patient, generally in terms of pulmonaryflow information.

The preferred reader within the spirometer base comprises a lightemitting diode (LED) and a photo detector respectively positioned onopposite sides of the reading slot. With this type of reader, the sensorunit tab must be at least translucent (and may of course be transparent)to permit passage of light therethrough. It has been found thatcharacterizing data in the form of a series of spaced apart bar-likeelements can be very accurately read by the reader of this preferredtype. Accordingly, in preferred practice, a transparent polyester stripwith such bar element characterizing information is applied to one faceof each sensor unit tab using an acrylic adhesive applied to theunderside of the strip during manufacture of the sensor unit.

The preferred sensor unit is also equipped with a specialized pressurechamber which has been designed to minimize the possibility of pathogencontamination. In particular, the tubular element includes a pressurechamber in operative communication with the interior thereof. Thepressure chamber is in the form of an elongated, concave channel formedin the outer wall of the tubular element, with at least one aperturecommunicating the channel with the interior of the tubular element; aweb of flexible synthetic resin tape is applied over the channel tocomplete the pressure chamber. In order to impede the passage ofcontaminants along the length of the pressure chamber, one or moreupstanding, inwardly extending obstructions or diverters are locatedwithin the channel, thus causing any such contaminants to traverse atortuous or serpentine path.

The sensor unit also has an elongated, tubular connection nipple or stemhaving an inlet opening in communication with the channel. A recessedregion or trap surrounds the inlet opening of the stem for collection ofcontaminants therein to prevent such contaminants from passing into thestem, thus providing a further degree of contamination prevention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a spirometry assembly in accordance withthe invention, made up of a spirometer and a sensor unit operativelycoupled thereto;

FIG. 2 is a side elevational view of the preferred sensor unit of theinvention;

FIG. 3 is an end view of the sensor unit illustrated in FIG. 2, viewingthe inlet end thereof;

FIG. 4 is an end view of the sensor unit of FIG. 2, viewing the tab endthereof and with the restrictor screen partially broken away toillustrate the internal design of the sensor unit;

FIG. 5 is a fragmentary side view of the sensor unit, shown with aportion of the web normally covering the pressure chamber broken away toreveal details of construction of the pressure chamber;

FIG. 6 is a fragmentary top view of the sensor unit, with a portion ofthe web normally covering the pressure chamber removed;

FIG. 7 is an enlarged, fragmentary vertical sectional view of the sensorunit illustrating in detail the pressure chamber and outlet stem;

FIG. 8 is an enlarged, fragmentary vertical sectional view taken throughthe outlet stem as depicted in FIG. 7;

FIG. 9 is a fragmentary view illustrating the sensor unit tab insertedwithin the spirometer reading slot; and

FIG. 10 is a fragmentary side view illustrating the sensor unit handleflange inserted within the reading slot during storage andtransportation of the spirometry assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to the drawings, and particularly FIG. 1, a spirometryassembly 20 is illustrated which broadly includes a spirometer 22 aswell as a sensor unit 24 operatively coupled thereto via a handleassembly 26.

The spirometer 20 is in the form of a hand-held, portable base 28equipped with an elongated reading slot 30, control and input buttons 32and output screen 34. The base 28 has a reader 36 (see FIG. 9)preferably in the form of a light emitting diode 38 and photodetector 40respectively disposed on opposite sides of reading slot 30. In addition,a pressure transducer and A to D converter are housed within base 28,along with a microprocessor-type signal processor and associatedcircuitry, all of such hardware being of conventional design.

The sensor unit 24 includes a single-use, disposable tubular element 42having an input end 44 and an opposed output end 46 covered with ascreen-type restrictor 48 attached by sonic welding. As shown, the body42 is of slightly tapered design along the majority of its length, buthas a frustoconical endmost section 50 leading to output end 46.

As best seen in FIGS. 5-8, an elongated, tubular, approximatelytangentially oriented integral outlet stem 52 is provided on element 42and presents an uppermost, obliquely oriented circular inlet opening 54.The inlet opening 42 communicates with a pressure chamber 56 in the formof an elongated, cross-sectionally concave channel 58 which isintegrally formed in the wall of element 42. A pair of spaced apertures60, 62 serve to communicate chamber 56 with the interior of element 42.As seen in FIGS. 6 and 7, the channel 58 has a pair of axially spacedapart, upstanding flow diverters 64, 66 therein between aperture 62 andinlet opening 54. It will be noted that the diverters, 64, 66cooperatively present a tortuous path for any contaminants which mightotherwise pass through the apertures 60, 62 during use of sensor unit24. In addition, the element 42 is configured to present a trap orrecessed area 68 around stem inlet opening 54. This provides a stillfurther protection against contaminants entering stem 52, i.e., suchcontaminants are contained and trapped within the recessed area 68beneath the inlet opening 54. In order to complete the pressure chamber56, a web of flexible adhesive synthetic resin material 70 is appliedover channel 58 and inlet opening 54.

An integral, laterally projecting tab 72 extends from the output end 46of tubular element 42. The tab 72 is dimensioned to fit within readingslot 30, and supports thereon a mylar strip 74 having a series ofelongated bar-like markings 76. At least the portion of tab 72supporting strip 74, and strip 74 itself, are translucent to allowpassage of light therethrough. The strip 74 having the markings 76 isapplied to each individual element 42 during manufacture ascharacterizing indicia for the respective element. Specifically, duringmanufacture, each individual element 42 is tested by passing a preciselymonitored flows of gas therethrough. The pressure conditions generatedwithin the respective element 42 under such test conditions are measuredand characterizing indicia, in the form of the strip 74 with markings 76thereon, is printed. This printed strip is then applied to the tab 72.

The preferred tubular element 42 is fabricated as an integral unit andis formed of an appropriate styrene-butadiene copolymer material such asK-Resin KR01, KR03 or BK10 sold by the Phillips Chemical Company. Therestrictor 48 is formed of commercially available wire cloth.

The handle assembly 26 includes an elongated syntheticresin handle body78 which is adapted to detachably support individual sensor units 24. Tothis end, the handle body 78 includes an upper arcuate surface 80 whichgenerally conforms with the curvature of tubular element 42, as well asa stem-receiving bore 82 sized to frictionally receive stem 52 (see FIG.7). The handle body also has an elongated passageway 84 extending frombore 82 to the bottom thereof. As best seen in FIGS. 2 and 3, the handlebody 78 has appropriately sized and located grips 86 as well as anoutwardly projecting, flange 88.

The handle assembly 26 also includes an elongated, flexible conduit ortube 90. One end of the tube 90 is secured to handle body 78 by means ofa barb connector (not shown) so that the tube is in communication withpassageway 84. The other end of tube 90 is connected to the underside ofbase 28 through a port leading to the pressure transducer within thebase.

In the use of assembly 20, the operator first obtains a sensor unit 24and the latter is attached to handle body 78 by insertion of stem 52into bore 82. The base 28 is then activated by pressing the appropriatecontrol button, and the tab 72 is inserted within reading slot 30. Thetab is passed along the length of the slot past reader 36 so that thereader can identify the location of the markings 76 on the strip 74.This characterizing indicia for the respective sensor unit 24 is thensent to the memory associated with the base signal processor.

In the next step, a patient induces gas flow through the tubular element42 by either blowing into or sucking air through the inlet end 44. Thepatient is normally asked to exhale into or inhale through the end 44for a specified period of time, such as six seconds. This in turngenerates positive or negative pressure conditions within the interiorof tube 42 and chamber 56. The pressure conditions within the chamber 56are measured multiple times over the exhale/inhale period by thebase-mounted transducer, owing to the communication established betweenthe transducer and chamber 56 through tube 90, passageway 84, bore 82and stem 52. The transducer thus generates pressure condition data andthis is also sent to the signal processor.

The signal processor receives the characterizing data and the pressurecondition data and calculates report information about the pulmonarycondition of the patient. The mathematical algorithms used to generatethe report information are known and a number of different algorithmscan be employed. For example, the characterizing and pressure conditiondata can be used in the following general equation to derive desiredpulmonary flow information by solving for F:

    K.sub.1 (F)+K.sub.2 (F.sup.2)+K.sub.3 (F.sup.3)=P.sub.T

where P_(T) is representative of the measured pressure conditions withinthe tube 42, F is the pulmonary flow and K₁, K₂ and K₃ arecharacterizing indicia encoded by the markings 76 during manufacture ofthe particular sensing unit 24. The output from the signal processor isdisplayed on output screen 34 of base 28 and can also be transferred viaa conventional cable to an output printer.

After a spirometry test is completed, the unit 24 used for that test isdetached from handle 78 and discarded. If a new test session is to becommenced for a different patient, a fresh sensor unit 24 is thenattached to the handle 78 and the above process is repeated. However, ifthe operator needs to move to a different location for the next session,the handle unit 78 is grasped and flange 88 thereof is pressed into slot30 as shown in FIG. 10. The flange 88 is configured so that the handleunit 78 is frictionally held against the body 28. As such, the entireassembly can be conveniently stored and handled until it is next to beused.

The assembly 20 can be used to develop any or all of the conventionallyused pulmonary function test data, e.g., FVC FEV₁, FEVI/FVC, FEV₃,FEF25-75%, PEF, FET, FIVC, PIF, FEF50%/FIF50% and MVV. In addition,while in the embodiment illustrated the pressure transducer is housedwithin the base 28, it would be feasible to alternately mount thetransducer within the handle unit 78. In such a case, an electricalconnection would be established between the transducer and themicroprocessor within the base 28.

We claim:
 1. A spirometry assembly for measuring a pulmonary conditionof a patient and comprising:a spirometer including a base presenting anelongated reading slot and a reader adjacent the slot; and a sensor unitcomprising an elongated tubular element having a reading tab, said tabincluding at least one characterizing indicium which characterizes aresponse parameter of the sensor unit upon flow of gas through saidtubular element, said reading slot being configured for receiving saidtab with said reader reading said indicium and generating characterizingdata representative of the indicium, said assembly including a measuringdevice in operative communication with the interior of said tubularelement for measuring a condition therein during patient-induced gasflow, and for generating condition data representative of suchcondition, and a signal processor for receiving said condition data andsaid characterizing data and responsive thereto for generating reportinformation about said pulmonary condition.
 2. The assembly of claim 1,said measuring device and said signal processor being housed within saidbase.
 3. The assembly of claim 1, said reader comprising a lightemitting diode and a photodetector respectively disposed on oppositesides of said reading slot.
 4. The assembly of claim 3, said tab beingat least translucent, and said characterizing indicium being applied toone face of said tab.
 5. The assembly of claim 1, said measuring devicecomprising a pressure transducer assembly for generating pressure datarepresentative of the pressure conditions within said tubular element.6. The assembly of claim 5, said signal processor operable for receivingsaid pressure data and said characterizing data responsive thereto forgenerating report information about said patient-induced gas flowthrough said tubular element.
 7. The assembly of claim 1, including apressure chamber on said sensor unit and in operative communication withthe interior of the tubular element, and an elongated tube incommunication with said pressure chamber and a pressure transducerhoused within said base.
 8. The assembly of claim 7, said pressurechamber including an elongated, concave channel formed in the outer wallof said tubular element with at least one aperture communicating saidchannel with the interior of the tubular element, there being at leastone upstanding diverter within said channel for causing any contaminantstherein to traverse a tortuous path along the length of the channel. 9.The assembly of claim 8, including an elongated, tubular connection stemextending from said tubular element and in communication with saidchannel, said connection stem presenting an inlet opening adjacent saidchannel, there being a recessed region surrounding said inlet openingfor collection of contaminants and preventing such contaminants frompassing into said stem.
 10. The assembly of claim 8, including a web ofadhesively secured material disposed over said channel.
 11. The assemblyof claim 1, including a handle detachably secured to said sensor unit,said handle including a flange, said flange being insertable within saidslot for transport of the base and handle.
 12. A method of measuring apulmonary condition of a patient comprising the steps of:providing aspirometry assembly including a spirometer having a base presenting aelongated reading slot and a reader adjacent the slot, and a sensor unitincluding an elongated tubular element having a reading tab, said tabhaving thereon at least one characterizing indicium which characterizesa response parameter of the sensor unit upon flow of gas through thetubular element; inserting said tab within said slot and causing saidreader to read said indicium and to generate characterizing datarepresentative of the indicium; causing said patient to induce a gasflow within said tubular element, measuring a condition within thetubular element representative of said gas flow therethrough, andgenerating condition data representative of said condition; andreceiving said condition data and said characterizing data and inresponse thereto generating report information about said pulmonarycondition.
 13. The method of claim 12, including the step of measuringthe pressure within said tubular element during said patient-induced gasflow therethrough.
 14. The method of claim 12, said characterizing databeing in the form of a series of bars, said reading step comprising thestep of passing said tab along the length of the slot.
 15. In aspirometry assembly for measuring a pulmonary condition of a patientincluding a spirometer having a signal processor and a sensor unitoperably coupled thereto, the improvement which comprises:at least onecharacterizing indicium carried by said sensor unit which characterizesa response parameter of the sensor unit; and a reader including areading slot for receiving said indicium carried by said sensor unitoperably coupled with said spirometer signal processor for reading saidindicium and generating characterizing data representative of theindicium.
 16. The assembly of claim 15, said reader being positionedadjacent said reading slot, said characterizing indicium being carriedon a tab affixed to said sensor unit, said tab being insertable withinsaid slot for reading of said indicium.